Borenstein Arie, Strauss Volker, Kowal Matthew D, Anderson Mackenzie, Kaner Richard B
Department of Chemistry, Ariel University, Ariel, 40700, Israel.
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
Small. 2019 Dec;15(52):e1904918. doi: 10.1002/smll.201904918. Epub 2019 Nov 22.
Producing highly oriented graphene is a major challenge that constrains graphene from fulfilling its full potential in technological applications. The exciting properties of graphene are impeded in practical bulk materials due to lattice imperfections that hinder charge mobility. A simple method to improve the structural integrity of graphene by utilizing laser irradiation on a composite of carbon nanodots (CNDs) and 3D graphene is presented. The CNDs attach themselves to defect sites in the graphene sheets and, upon laser-assisted reduction, patch defects in the carbon lattice. Spectroscopic experiments reveal graphitic structural recovery of up to 43% and electrical conductivity four times larger than the original graphene. The composites are tested as electrodes in electrochemical capacitors and demonstrate extremely fast RC time constant as low as 0.57 ms. Due to their low defect concentrations, the reduced graphene oxide-carbon nanodot (rGO-CND) composites frequency response is sufficiently fast to operate as AC line filters, potentially replacing today's electrolytic capacitors. Using this methodology, demonstrated is a novel line filter with one of the fastest capacitive responses ever reported, and an aerial capacitance of 68.8 mF cm . This result emphasizes the decisive role of structural integrity for optimizing graphene in electronic applications.
制备高度取向的石墨烯是一项重大挑战，这限制了石墨烯在技术应用中充分发挥其潜力。由于晶格缺陷阻碍了电荷迁移，石墨烯令人兴奋的特性在实际块状材料中受到阻碍。本文提出了一种通过对碳纳米点（CNDs）与三维石墨烯的复合材料进行激光辐照来改善石墨烯结构完整性的简单方法。碳纳米点附着在石墨烯片层的缺陷部位，在激光辅助还原后，修补碳晶格中的缺陷。光谱实验表明，石墨结构的恢复率高达43%，电导率比原始石墨烯大四倍。该复合材料在电化学电容器中作为电极进行了测试，并展示出低至0.57 ms的极快速RC时间常数。由于其低缺陷浓度，还原氧化石墨烯-碳纳米点（rGO-CND）复合材料的频率响应足够快，可作为交流线路滤波器工作，有可能取代当今的电解电容器。使用这种方法，展示了一种新型线路滤波器，其具有有史以来报道的最快电容响应之一，以及68.8 mF/cm²的面电容。这一结果强调了结构完整性在优化电子应用中石墨烯方面的决定性作用。
